Techniques for profile binning and analysis of eigenvector composite spectra: Comparing Hβ and Mgiiλ2800 as virial estimators

DOI: 
10.1016/j.asr.2013.09.039
Publication date: 
01/10/2014
Main author: 
Sulentic J.W.
IAA authors: 
Sulentic J.W.;Del Olmo A.;Plauchu-Frayn I.
Authors: 
Sulentic J.W., Marziani P., Del Olmo A., Plauchu-Frayn I.
Journal: 
Advances in Space Research
Publication type: 
Article
Volume: 
54
Pages: 
1406-1413
Number: 
Abstract: 
We review the basic techniques for extracting information about quasar structure and kinematics from the broad emission lines in quasars. We consider which lines can most effectively serve as virial estimators of black hole mass. At low redshift the Balmer lines, particularly broad Hβ, are the lines of choice. For redshifts greater than 0.7 - 0.8 one can follow Hβ into the IR windows or find an Hβ surrogate. We explain why UV Civλ1549 is not a safe virial estimator and how Mgiiλ2800 serves as the best virial surrogate for Hβ up to the highest redshift quasar known at z≈7. We show how spectral binning in a parameter space context (4DE1) makes possible a more effective comparison of Hβ and Mgii. It also helps to derive more accurate mass estimates from appropriately binned spectra and, finally, to map the dispersion in MBH and Eddington ratio across the quasar population. FWHM MgII is about 20% smaller than FWHM Hβ in the majority of type 1 AGN requiring correction when comparing MBH estimates from these two lines. The 20% of sources showing narrowest FWHM Hβ (<4000 km s -1) and strongest FeII (RFe≥1.0) emission (we call them bin A3-4 sources) do not show this FWHM difference and a blueshift detected in MgII for these sources suggests that FWHM Hβ is the safer virial estimator for these extreme Eddington emitters. © 2014 Published by Elsevier Ltd.
Database: 
WOK
SCOPUS
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2014AdSpR..54.1406S/abstract
ADS Bibcode: 
2014AdSpR..54.1406S
Keywords: 
Line: profile; Line:formation; Quasars: emission lines; Quasars: general